1. Technical Field
The disclosure relates in general to a semiconductor structure and a manufacturing method for the same, and more particularly to a HV device and a manufacturing method for the same.
2. Description of the Related Art
In the semiconductor technique, the feature size has been reduced. In the meantime, the rate, the efficiency, the density and the cost per integrated circuit unit have been improved. For example, a diode of a semiconductor structure, such as Schottky diode, can be applied for an asynchronous device. A conventional Schottky diode is formed by forming a metal contact, a field oxide isolation (FOX) and an N-type heavily doped portion on a N-type substrate. The metal contact and the N-type heavily doped portion, respectively on the substrate on two opposite sides of the single FOX, are electrically connected to an anode and a cathode respectively.
The asynchronous device usually have two power MOSFETS, respectively disposed at a high side and a low side of the device. The Schottky diode can be applied to the MOSFET at the low side, for reducing the power loss in a buck DC-to-DC conversion. However, when operated by a reverse bias, the conventional Schottky diode has a leakage current that seriously influent the efficiency of the device disadvantageously. The leakage current results in the power loss in the circuit. Referring to FIG.1, for example, when operated by a reverse bias, the leakage current of the conventional Schottky diode is gradually increased with the voltage with a linear relationship therebetween. In addition, the breakdown down of the conventional Schottky diode would not be happened. Therefore, when applied for the HV device, the conventional Schottky diode has the shift voltage level.